Practically Classics Forum

I have been rebuilding a dizzie for my B series engine. When I got down to the counterweight springs, they were all magled as if someone had 'adjusted' them with a pair of pliers to close them up a little.

I have bought a set of the dizzie springs from Moss-Europe to fit but I have a question on fitting.

Does it matter which spring is fitted where, should the light weight spring be close to the toe on the advance plate, or should the heavier spring be fitted there, or does it matter which spring is fitted where?

I am going to play around with the spring rates until I find something that suits the state of tune of the car, but need to know which side to clip them.

Any help or advice will be appreciated.

Thanks,

Chris

I had the same problem when fettling a dizzy on an MGB a few years back - couldn't find any data anywhere on the spring config. In the end I rebuilt it with the replacement springs going in the same place as the originals i.e. re-assembly being the reverse of dismantling.
Not much help to you I know as your springs are mangled
There is a website owned by an MG specialist Simon Lacey on Google - he shows a pictorial rebuild of a 25D but there is no specific info on the springs other than a lovely pic of them installed - just google Lucas Distributor and you will find him.
Have you considered a digital replacement for your Dizzy - the 123 is a costly example but there are items on e-bay for less than £50 which incorporate electronic ignition and come with brand new everything else. I know they are cheap but not necessarily nasty, I have run a £19 module type ignition on my Princess for almost two years now and it has transformed the engines prformance

I've got several old BMC workshop manuals which describe how to overhaul a 25D distributor and none of them mention a specific order for the springs, so I assume that it doesn't matter.

going against what you are probably trying to do here but I just bought a new replacement for my landy series 3 (25D) for £20 delivered off fleaby.

Just a thought and good quality as it now runs very smoothly when previously it just wouldnt rev.

Thanks Guys,

The thing about the springs and maximum advance are that they vary from make to make and model to model, so a landrover 25D will in all liklihood be totally different from an MGB 25D.

My original Marina 45D had a maximum 15 degree advance stop and the older 25D I now have has 10 degree advance stop. Peter Burgess book on tuning B Series recommends the 10 degree advance stop which is doubled to 20 degrees when in use (I don't understand how exactly) and then the static advance of 10-14 degrees. Giving an overall maximum advance of say 34 degrees when above 3000 revs.

The springs control the rate that the advance goes from the static setting of say 10 degrees up to the maximum 34 degrees. The two springs are different strengths and lengths so that one engages before the other, starting and rising fast as the bob weights spin out taking the spring posts with them and as the second spring kicks in and slows down the rate of advance.

So that's the theory, I guess the only way is to fit the thing and see what happens.

MarinaCoupe wrote: Peter Burgess book on tuning B Series recommends the 10 degree advance stop which is doubled to 20 degrees when in use (I don't understand how exactly)

Presumably that means 10 degrees on the distributor, which as it runs at half crankshaft speed equates to 20 degrees there......Possibly.

Harvey,

Yes that makes sense.

"The thing about the springs and maximum advance are that they vary from make to make and model to model, so a landrover 25D will in all liklihood be totally different from an MGB 25D."

Not sure if it's of any use but in MGB Electrical Systems by Rick Astley, [not "that" one I hope] on page 108 is a graph showing the advance curves for the Lucas dizzies by part no. It too, goes on about worn advance springs but doesn't tell you any specifics. I'd have thought somebody like Aldon would have told you if you give them a ring. Not suer where you're based but Mike Entwistle's MG place in Prestwich [Mcr] has a distributor test rig too that he put mine on a while ago [it was fubared].

HTH.